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BIOL5_Lab2.6_Tetanus

Page 1: Lab 2.6: Tetanus, Electromyography

  • Chapter 12

Page 2: Overview

  1. Tetanus

    • Distinction between the disease and physiological term.

  2. Twitch contraction

  3. Twitch vs Summation

  4. Incomplete vs Complete Tetanus

  5. Frequency of Stimulation

Page 3: Disambiguation: Tetanus

  • Tetanus (Disease)

    • Caused by Clostridium tetani.

    • Toxin released during anaerobic metabolism causes painful muscle contractions.

    • Tetanus toxin binds to inhibitory neurons, leading to sustained muscle contraction for varying durations (minutes to weeks).

  • Tetanus (Physiology)

    • Refers to sustained muscle contractions that are not painful or pathogen-induced.

Page 4: Twitch Contraction 1

  • Twitch Contraction :

    • Brief contraction of all muscle fibers in a motor unit due to a single action potential.

  • Refractory Period:

    • Period of excitability loss where the cell cannot respond to a second stimulus if it occurs too soon.

Page 5: Twitch Contraction 2

  • Phases of Twitch Contraction:

    1. Latent Period

    2. Contraction Period

    3. Relaxation Period

Page 6: Twitch and Summation

  • Twitch:

    • Single rapid contraction and relaxation of muscle fibers.

  • Summation:

    • If a second stimulus occurs before the muscle relaxes from the first twitch, the second twitch is stronger.

    • Allows graded contractions through stimulation of different numbers of fibers.

Page 7: Visuals of Muscle Function

  • (a) Stimulus leading to Muscle Twitch

  • (b) Summation of Twitches from Multiple Stimuli

Page 8: Incomplete vs Complete Tetanus

  • Incomplete Tetanus (Unfused Tetanus):

    • Occurs with increasing frequency of electrical shocks, leading to increased muscle tension below maximum.

  • Complete Tetanus (Fused Tetanus):

    • Rapid stimulation leads to no relaxation and results in a smooth, sustained contraction.

Page 9: Frequency of Stimulation

  • Wave Summation:

    • Occurs when a second action potential triggers a contraction before the cell has relaxed, resulting in a stronger contraction.

  • Incomplete Tetanus:

    • Characterized by 20-30 action potentials per second, causing wavering, sustained contraction.

  • Complete Tetanus:

    • Achieved with 80-100 action potentials per second, resulting in a sustained contraction.

Page 10: Tetanus Types and Shocks

  • Incomplete Tetanus:

    • Results from 5 shocks per second.

  • Complete Tetanus:

    • Results from 60 shocks per second, leading to fatigue.

Page 11: Frequency of Stimulation: Myogram

  • Analysis of contraction time and force production as influenced by different stimulation conditions.

Page 12: Tone and Contractions

  • Muscle Tone:

    • Weak, involuntary contractions in resting muscles generating low tension.

    • Functions: Stabilizes body, maintains organ pressure, and regulates blood pressure.

  • Flaccid Muscles:

    • Condition of limp muscle due to motor neuron damage.

Page 13: Isotonic vs Isometric Contractions

  • Isotonic Contraction:

    • Muscle length changes while tension remains constant, producing movement at a joint.

    • Types:

      • Concentric (Shortening)

      • Eccentric (Lengthening)

  • Isometric Contraction:

    • Muscle contracts without changing length; no joint movement occurs.

Page 14: Visual Representation of Muscle Contractions

  • Concentric Contraction:

    • Muscle contracts and shortens.

  • Eccentric Contraction:

    • Muscle elongates while active.

  • Isometric Contraction:

    • Muscle remains unchanged in length while generating force.

Page 15: Muscle Levels Analysis

  • Content overview on muscle behavior and function at the level of a muscle.

Page 16: Smooth vs Jerky Motion

  • Discussion on the mechanisms allowing for smooth muscle motion over jerky movements.